Multi-stage gas lift fluid pump system

ABSTRACT

A gas lift pump system utilizing high pressure gas from a pump delivered down a pipe string to a jet pump at the producing zone of a well to provide an initial lift for the fluid and to admix gas and fluid, and a series of supplemental lift devices at spaced intervals along the vertical extent of the well. The supplemental lift devices include a check valve which has the effect of reducing the total head of fluid which each section is called upon to lift and a gas chamber, in conjunction with a pipe mounted within the delivery tubing, to force the fluid into succeeding sections and further promote mixing. The fluid is raised stage by stage until it reaches the surface where the gas is removed and re-cycled.

. United States Patent 1191 Newbrough 1 MULTI-STAGE GAS LIFT FLUID PUMP1 51 Feb. 27, 1973 Primary Examiner-William L. Freeh SYSTEM AssistantExaminer-Richard E. Gluck [76] inventor: Joseph S. 'Newbrough, 6250Primmmmey-car l Brown and rose Drive, La Mesa, Calif. 92041 [57]ABSTRACT [22] F1led: Feb. 16, 1971 A gas lift pump system utilizing highpressure gas from PP N04 115,209 a pump delivered down a pipe string toa jet pump at the producing zone of a well to provide an initial lift 52US. Cl. ..417/108, 137 209, 417/172 for the fluid and to admiX g andfluid, and a series of [51] Int. Cl ..F04t 1/18, B67d 5/54 Supplementallift devices at spaced in er ls al ng the [58] Field of Search..412/108, 109, 110, 111, 172; vertical extent of the well. Thesupplemental lift 137/209, 210 devices include a check valve which hasthe effect of reducing the total head of fluid which each section is[56] References Cited called upon to lift and a gas chamber, inconjunction with a pipe mounted within the delivery tubing, to UNITEDSTATES PATENTS force the fluid into succeeding sections and further1,374,952 4/1921 Rogers ..4l7/109 promote mixing. The fluid is raisedstage by stage until 3,239,609 12/1966 P810 ....417/108 it reaches thesurface where the gas is removed and 2,674,202 4 1954 Kelly et al......417/172 re cyc1ed 1,811,295 6/1931 Blow ..4l7/108 l 9 Claims, 3Drawing Figures.

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26 STORAGE 32 SEPARATOR A6 FLOW T0 011. STORAGE TANK CHOKE, an x k 3 .I-

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2| Ayn Aun- PATENTE FEB27 I975 SHEET 2 OF 2 ATTORNEYS MULTI-STAGE GASLIFT FLUID PUMP SYSTEM BACKGROUND OF THE INVENTION It is common practicewhen providing for the raising of fluids, particularly petroleum, fromwells, to utilize a pumping technique in the absence of natural flow orto supplement the natural flow to make more efficient utilization of andconserve the reservoir gas. A frequently used technique employs areciprocating sucker-rod string, activating a mechanical pump located inthe producing zone. These, units require many man hours to install andare subject to high maintenance cost. In addition the long sucker rodstring induces large friction losses and wear.

To overcome the disadvantages associated with the mechanicalreciprocating method of lifting the fluids to be produced, various gaspowered pumping techniques have been proposed. With the exception ofrelatively shallow wells, these techniques require the utilization of anextremely high pressure to force the fluids from the producing zone. Thehigh pressures required may be beyond the capability of even the mostexpensive and complex pumping systems and the technique is limited bythe ability of the pipe string to withstand the pressures proposed toaccomplish the lifting of the fluids in multiple stages so asto avoidexcessive pressures for any one stage. These devices normally injectadditional gas at multiple points between the producing zone and thesurface to supplement the power of the initially utilized gas. As aconsequence, these devices require a large volume of gas with theconsequent inefficiencies in the pumping equipment and a large increasein the requirement for separating the gas and the oil if the gas is tobe re-cycled. q

Thus it would be advantageous if a low volume of relatively low pressuregas could be fully utilized to lift successive units of oil to thesurface and then removed from the oil for re-use.

SUMMARY OF THE INVENTION An exemplary embodiment of the multi-stage, gaslift, fluid pump system of the invention comprises a surface pump toproduce high pressure gas for introduction into the annulus between theproduction string and the producing tubing. The gas is conveyed in theannulus to the producing zone where a side wall packer prevents furthertravel down the annulus. A jet pump is located above the packer in theproducing tubing and produces a venturi effect where the oil isentrained in the gas and forced upwardly at high velocity producing athorough admixture of gas and oil with sufficient pressure to raise theresultant mixture a considerable distance.

The first supplemental lift device is located spaced a vertical distancefrom the jet pump which approximately corresponds to the capability ofthat pump to raise the fluids in a single lift. The supplemental liftdevice comprises a pipe section suspended from a joint within thetubing. The pipe is approximately feet in length with the last 2 feetthereof being provided with a plurality of openings for admitting theoil and gas mixture. A fluid gas interface is formed within eachsupplemental lift device at the upper end of this perforated area and areservoir of gas is thus retained in the annulus between thesupplemental lift device pipe and the induced. Numerous devices havebeen.v

production tubing. The pressure of gas in this chamber together with thegas pressure already admixed with the oil and that being released fromthe oil forces the oil through the perforations and effectsa thoroughmixing of the gas and oil which then progresses through the supplementallift device pipe to its upper end where a check valve in the form of aball and cooperating seat is located. When sufficient gas pressure isavailable the ball is forced off its seat and the mixture flows aroundthe ball and into the succeeding section of producing tubing. The ballprevents reverse flow of the fluids and separates the producing tubinginto a series of steps, each step having a supplemental lift deviceassociated with it. In normal operation, the oil is lifted inintermittent steps, each section of oil being lifted to the succeedingsection as sufficient pressure becomes available and when the succeedingsection is relatively empty of the previously lifted column of oil. Thelifting process is assisted by the additional gas volume which iscreated as the fluids are raised from the relatively high pressureconditions in the producing zone towards atmospheric pressure at thesurface. The reduction of pressure results in the release of dissolvedgases from the fluid and this additional volume thoroughly mixed by eachsucceeding supplemental lift device aids in the overall lifting effect.I

The action continues through successive stages until the gas-oil mixtureis raised to the surface, where it is directed to a conventionalpressure type separator which removes the gas from the mixture forre-cyclin g.

It is therefore an object of this invention to provide a new andimproved multi-stage gas lift fluid pump system.

It is another object of this invention to provide a new and improved gaslift pump system which utilizes a flow of gas injected at a single pointwithin a well string.

It is another object of this invention to provide a new and improved gaslift pump system with provision for re-cycling of the gas used to liftthe produced fluid.

It is another object of this invention to provide a new and improved gaslift pump system which maintains the produced fluid in thorough mixturewith the lifting gas.

It is another object of the invention to provide a new and improved gaslift pump system which reduces the cost of producing fluids from wells.

It is another object of the invention to provide a new and improved gaslift pump system which requires relatively little maintenance.

It is another object of the invention to provide a new and improved gaslift pump system which incorporates a series of check valves to reducethe total head lifted by any one stage.

Other objects and many attendant advantages of this invention willbecome more apparent upon a reading of the following detaileddescription and an examination of the drawings wherein like referencenumerals designated like parts throughout.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view, partially insection of the complete apparatus.

FIG. 2 is an enlarged sectional view taken on line 2 2 of FIG. 1.

FIG. 3 is an enlarged sectional view taken on line 3- 3 of FIG. 1.

Referring now to the figures, there is illustrated a multi-stage gaslift fluid pump system. The entire system is illustrated in FIG. 1 andincludes a well pipe installation including a surface pipe 12 surroundedby a cement casing 14. The production string 16 is carried within thesurface pipe 12 for a portion of the total depth of the well and theremainder of the well is in direct contact with the strata through whichthe production string passes. Where the production string extends intothe producing zone 18 a plurality of oil entry perforations 20 areprovided. A producing tubing 22 is shown located within the productionstring and extending downwardly at least as far as the producing zone.

The annulus 17 between the producing tubing 22 and the production string16 is shown to be open for the passage of gas throughout its lengthexcept that the downward travel of gas is limited by a side wall packer24 shown located just above the producing zone. At the casing head, theannulus is sealed and is penetrated by a gas delivery pipe 26 which iscapable of supplying gas under pressure from pump 28 to the gas entrynozzle or jet pump 30 through the annulus 17. The oil and gas liftedfrom the well are delivered through pipe 32 and flow choke 34 to aseparator 36. The gas segregated by the separator is conveyed by a pipe38 to a storage facility (not shown). The segregated gas is directedthrough a pipe 40 to a gas storage facility 43 or is returned to the gaspump for re-use through pipe 42. The jet pump 30 is shown to comprisetwo generally conical upwardly curving sections 44 and 46 which convergetoward their upward end to form a nozzle like termination. Gas passingthrough these nozzles exits the upper end of the nozzle at high velocityand creates a low pressure area in accordance with the well knownBernoulli effect, drawing the oil through the orifice 50. The side wallpacker 24 is effective to seal the gas from travelling further down thewell and forcing the entire gas supply to pass through the jet pump. Acheck valve 52 is provided to prevent backwards flow of the oil underthe influence of gas pressure.

FIG. 3 illustrates the details of the supplemental lift device which isconveniently supported from the joint coupling 54 between successivesections 56 and 58 of the producing tubing 22. The device includes apipe 60 having an outside diameter considerably smaller than the insidediameter of the producing tubing. A ball check valve 62 is illustratedand includes a seat portion 64 and retainer 66.

The pipe 60 is approximately ten feet in length with the last two feetthereof provided with a plurality of openings 61. The gas-oil interfaceis maintained at approximately the level of uppermost openings 61. Theannulus 63 between the supplemental lift device pipe and the productionstring provides a chamber for the gas which has separated from the oil.

The operation of the system will be considered with respect to its usein a non-flowing well. In such a well the residual pressure in thereservoir will cause the oil to be forced upwards in the productionstring to a level somewhat above the producing zone. For example, in theinstant device, the level might be considerably above the area of thejet pump. Thus the initial operation with respect to commencing pumpingwould be to apply gas pressure from the gas storage facility 43 throughthe use of pump 28 so as to force the oil down the production string.The side wall packer is effective to force the oil through the jet pumpand into the producing tubing. The increased pressure forces check valve52 against its seat so as to prevent the flow of oil into the producingzone and the oil therefore flows upwardly through the producing tubinguntil all the oil is exhausted and only gas is flowing through the jetpump. The gas flow results in a low pressure zone which forces the oilthrough the orifice 50. The reduced pressure eventually communicateswith the check valve 52 and additional oil is drawn in by the action ofthe jet pump. From this point forward, during the operation of thesystem, the check valve 52 will be held away from its seat. Under theaction of the jet pump the oil is thoroughly admixed with gas and isforced upwards a considerable distance into the vicinity of thesupplemental lift device. At this point the lifting power of the gas isbeginning to dissipate because of the separation of the gas and oil intodistinct phases and because the limited gas pressure is not capable oflifting the oil against excessive heads. The annulus between thesupplemental lift device and the producing tubing fills with theseparated gas which forms a reservoir down to the level of the firstperforations of the supplemental lift device pipe. As the devicesachieve stabilization the quantity of gas entering the system will allbe passing through the perforations and by this action will thoroughlymix again with the oil, producing an additional lifting effect andraising the oil past the check valve into the next section of producingtubing.

The action of the subsequent supplemental lift device is similar, witheach device remixing the oil and gas to obtain maximum lifting effectfrom the originally induced gas as well as the gas produced from the oilby the result of the reduction in overall pressure. The flow between thesupplemental lift devices, for example, between the first lift deviceand that next above it is intermittent, that is, the flow from the firstdevice into the next following device takes place only when the fluid inthe upper string has been lifted past the following devices check valve,and no head holds the check valve against its seat. When theseconditions prevail, the oil, under the influence of the lifting gas, canlift the check valve from its seat and flow into the following sectionof producing tubing without the necessity of lifting a large column ofoil. Thus the oil is lifted in stages until it reaches the casing headfrom which it flows through pipe 32 and flow choke 34 to the separator36. The separator may be any one of several well known types which areeffective to segregate the two components of the mixture reaching thesurface, e.g., gas and oil. Any gas lost in the process is replaced fromthe LPG storage facility which maintains the volume of gas circulatingin the system at a constant value.

Having described my invention, I now claim:

1. In a gas lift pump including a source of gas under pressurecommunicating with a pump means at the lower end of tube extending intothe proximity of a quantity of fluid to be pumped, that improvementcomprising:

a plurality of supplemental lift means for utilizing a flow of gasthrough said tubing to lift said fluid,

and said supplemental lift means comprising a length of pipe mountedwithin said tubing and having a portion adjacent its lower endperforated to admit fluid and gas. 2. The improved pump system of claim1 wherein, said length of pipe includes a check valve mounted at itsupper end. 3. That improved pump system as claimed in claim 1 wherein,

said gas enters said tubing and only at the portion of said tubing inproximity to said quantity of said fluid. 4. That improved gas liftsystem as claimed in claim 1 wherein,

said pump means comprises a jet pump, said tubing is suspended within aproduction string of pipe in a well, and said source of gas beinglocated at the upper end of the producing string and communicating withsaid jet pump through the annulus formed between said production stringand said tubing. 5. The improved gas lift pump system as claimed inclaim 1 wherein,

said supplemental lift means further comprises, check valve means forpreventing substantial flow of fluid from said tubing means above saidcheck valve into said length of pipe. 6. The improved gas lift pumpsystem as claimed in claim 5 wherein,

said check valve comprises a ball check valve mounted in proximity tothe point of suspension of said length of pipe.

7. The improved gas lift pump system as claimed in claim 1 furtherincluding,

a side wall packer means mounted between said production string and saidtubing for forcing the gas from said source of gas to flow into said jetpump.

8. The improved gas lift pump system as claimed in claim 11 furtherincluding,

supplemental check valve means for preventing the backward flow of fluidduring the initial actuation of the system,

and said supplemental check valve means being located in said tubingbelow said jet pump means.

9. The improved gas lift pump system as claimed in claim 1 furtherincluding,

separator means for separating the gas from said fluid after said fluidis raised to the top of the tuband pump means for recirculating theseparated gas for pumping additional fluid.

1. In a gas lift pump including a source of gas under pressurecommunicating with a pump means at the lower end of tube extending intothe proximity of a quantity of fluid to be pumped, that improvementcomprising: a plurality of supplemental lift means for utilizing a flowof gas through said tubing to lift said fluid, and said supplementallift means comprising a length of pipe mounted within said tubing andhaving a portion adjacent its lower end perforated to admit fluid andgas.
 2. The improved pump system of claim 1 wherein, said length of pipeincludes a check valve mounted at its upper end.
 3. That improved pumpsystem as claimed in claim 1 wherein, said gas enters said tubing andonly at the portion of said tubing in proximity to said quantity of saidfluid.
 4. That improved gas lift system as claimed in claim 1 wherein,said pump means comprises a jet pump, said tubing is suspended within aproduction string of pipe in a well, and said source of gas beinglocated at the upper end of the producing string and communicating withsaid jet pump through the annulus formed between said production stringand said tubing.
 5. The improved gas lift pump system as claimed inclaim 1 wherein, said supplemental lift means further comprises, checkvalve means for preventing substantial flow of fluid from said tubingmeans above said check valve into said length of pipe.
 6. The improvedgas lift pump system as claimed in claim 5 wherein, said check valvecomprises a ball check valve mounted in proximity to the point ofsuspension of said length of pipe.
 7. The improved gas lift pump systemas claimed in claim 1 further including, a side wall packer meansmounted between said production string and said tubIng for forcing thegas from said source of gas to flow into said jet pump.
 8. The improvedgas lift pump system as claimed in claim 11 further including,supplemental check valve means for preventing the backward flow of fluidduring the initial actuation of the system, and said supplemental checkvalve means being located in said tubing below said jet pump means. 9.The improved gas lift pump system as claimed in claim 1 furtherincluding, separator means for separating the gas from said fluid aftersaid fluid is raised to the top of the tubing, and pump means forrecirculating the separated gas for pumping additional fluid.